Process for separation of phenanthrene

ABSTRACT

SEPARATION OF PHENANTHRENE FROM A SOLUTION OF A MIXTURE OF ANTHRACENE AND PHENANTHRENE IN LOWER ALCOHOL OR KETONE, UP TO 30% AQUEOUS MIXTURE THEREOF, OR MIXTURES THEREOF, BY SELECTIVELY PRECIPITATING THE PHENANTHRENE BY THE ADDITION OF WATER.

United States Patent O 3,793,387 PROCESS FOR SEPARATION OF PHENANTHRENE Yon-Chung Sun, Midland, Mich., assignor to The Dow Chemical Company, Midland, Mich. No Drawing. Filed Apr. 6, 1973, Ser. No. 348,777

. Int. Cl. C07c 7/02, 15/28, 15/30 US. Cl. 260-675 6 Claims ABSTRACT OF THE DISCLOSURE Separation of phenanthrene from a solution of a mixture of anthracene and phenanthrene in lower alcohol or ketone, up to 30% aqueous mixture thereof, or mixtures thereof, by selectively precipitating the phenanthrene by the addition of water.

BACKGROUND OF THE INVENTION Phenanthrene and anthracene are useful intermediate chemicals, especially in the dye industry. These compounds are found together in a petroleum fraction boiling in the range 340345 C. obtained from refinery operations. Since each compound has desirable properties, it must be separated to be useful. Many processes have been proposed for their separation. A compendium of such processes is found in Canadian Pat. 557,983. The patent also discloses a process for obtaining anthracene by dissolving away the impurities by leaching the distillate fraction with alcohol or ketones. The present process is an extension of the process is an extension of the process of Canadian Pat. 557,983 in that the phenanthrene of the leach liquor can now be recovered with little or no anthracene present.

BRIEF DESCRIPTION OF THE PRESENT INVENTION A mixture of anthracene and phenanthrene can be separated one from the other by adding to a mixture thereof in a lower alkanol or a lower ketone or an aqueous, up to 30 percent by weight water, lower alkanol or ketone or mixture thereof to selectively precipitate the phenanthrene from solution. The solution containing principally the phenanthrene and usually saturated with anthracene but not more than 10 percent by weight, based on the total solute, of anthracene, can be selectively caused to precipitate the phenanthrene by adding water in amounts up to 200 percent by weight of the solvent to the solution. Good results are obtained when substantially anhydrous alcohol or ketone is employed to dissolve the phenanthrene away from the anthracene and water is added in an equal volume to the alcohol or ketone at temperatures from room temperature to about 80 C., the lower melting point of the phenanthrene-anthracene mixture.

It is, of course, to be understood that any impurities which accompany the phenanthrene-anthracene fraction solubilized will also be dissolved to a great extent in the alcohol or ketone. However, these impurities are not precipitated in the practice of the present invention in detrimental quantities. Thus, the phenanthrene obtained is substantially free of these impurities.

Alcohols and ketones found useful in the practice of the present invention are the C to C monoalkanols, e.g., methanol, ethanol, propanol, isopropanol, butanol, isobutanol, tert. butanol, and the lower aliphatic ketones having 3 to 4 carbon atoms, e.g., acetone, methyl ethyl ketone, diethyl ketone, and the like.

The amount of alcohol or ketone employed should be sufiicient to theoretically dissolve all of the phenanthrene but insufficient to dissolve to any great extent the anthracene, for example, one part of the petroleum fraction per 1.5 to 4 parts of solvent.

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DETAILED DESCRIPTION OF THE INVENTION Example 1 To 50 ml. of saturated antharcene and phenanthrene acetone solution, such as obtained by leaching a commercially produced petroleum fraction boiling in the 335- 345 C. range with acetone containing 21.4% phenanthrene and 1.8% anthracene (anthracene:phenanthrene= 8.6%:9l.4%), was added 50 m1. of distilled water. A white precipitate formed and was separated from the liquid phase by centrifugation. The separated solid was 98.7% phenanthrene and 1.3% anthracene. Total material balance indicated that approximately of the dissolved phenanthrene was selectively precipitated.

Example 2 To 50 ml. of an ethyl alcohol solution of anthracene and phenanthrene containing 4.9% phenanthrene and 0.4% anthracene (anthraoenezphenanthrene 7.5%:92.5%) was added 50 ml. water. The solid which precipitated was recovered by centrifugation. The phenanthrene purity was 98.4% and the recovery was about 70%.

I claim:

1. The method for separating phenanthrene from a solution thereof with anthracene in at least one of an alkanol of 1 to 4 carbon atoms, a ketone of 3 to 4 carbon atoms, aqueous mixtures thereof with up to 30% water or mixtures thereof comprising selectively precipitating the phenanthrene by the addition of water up to about 200% by weight based on the solvent.

2. A method for separating phenanthrene from anthracene comprising:

preparing a solution of phenanthrene and anthracene in a solvent selected from the group consisting of at least one of C lower monoalkanols, C lower aliphatic ketones, mixtures thereof, or their 3040% aqueous solutions at from room temperature to about C., and

precipitating the phenanthrene from the solute by adding water to the solute;

said solvent being employed in amounts of from 1.5

to about 4 parts of solvent per part of mixture being treated on a weight basis; and

said water being employed in up to about 200% by weight based on the solute to precipitate the phenanthrene.

3. A method for separating phenanthrene from anthracene comprising:

treating a mixture of phenanthrene and anthracene with a solvent selected from the group consisting of C lower aliphatic ketones, which may contain up to 30% water at from room temperature to about 80 C., and precipitating the phenanthrene from the solute by adding water to the solute;

said solvent being employed in amounts of from 1.5

to about 4 parts of solvent per part of mixture being treated on a weight basis; and

said water being employed in up to about 200% by weight based on the solute to precipitate the phenanthrene.

4. A method for separating phenanthrene from anthracene comprising:

treating a mixture of phenanthrene and anthracene with a solvent selected from the group consisting of C lower monoalkanols which may contain up to 30% water at from room temperature to about 80 C., and precipitating the phenanthrene from the solute by adding water to the solute;

said solvent being employed in amounts of from 1.5 to

about 4 parts of solvent per part of mixture being treated on a weight basis; and

said water being employed in up to about 200% by weight based on the solute to precipitate the phenanthrene. 5. A method for separating phenanthrene from anthracene comprising:

treating a mixture of phenanthrene and anthracene with ethanol at from room temperature to about 80 C. and precipitating the phenanthrene from the solute by adding 100% by weight based on the solute of water to the solute; said solvent being employed in amounts of from 1.5 to about 4 parts of solvent per part of mixture being treated on a weight basis. 6. A method for separating phenanthrene from anthracene comprising:

References Cited UNITED STATES PATENTS 4/1954 Andrews 260-675 2/1957 Nickolls et a1. 260-675 11/1966 Joo et a1 260-675 7/1967 Ab Der Halden 260-675 treating a mixture of phenanthrene and anthracene with 15 CURTIS R. DAVIS, Primary Examiner acetone at from room temperature to about 80 C. 

